Endoscopic ultrasound and magnetic resonance cholangiopancreatography in patients with idiopathic acute pancreatitis.

Background: The efficacy of endoscopic ultrasonography (EUS) to diagnose idiopathic acute pancreatitis has been demonstrated but that of magnetic-resonance cholangiopancreatography (MRCP) remains unclear.

Aims: The aim of our study was to prospectively compare the results of EUS and MRCP to diagnose idiopathic acute pancreatitis when performed later after an acute attack.

Methods: All patients admitted to our center for acute pancreatitis over a 2-year period received first-line investigations that included medical history, standard biological measurements, abdominal ultrasound, and computerized tomography. If no etiology was found, second-line investigations were scheduled at 2 months (or more if there was severe pancreatitis), which included clinical examinations, biological parameters, EUS, and MRCP.

Results: A total of 128 consecutive patients were included (male: 80, mean age: 55.3 years). After first-line investigations, 41 patients with idiopathic acute pancreatitis underwent second-line investigations and were followed-up (38 patients had both EUS and MRCP). EUS and/or MRCP led to recognize a possible etiology of pancreatitis in 19 patients (50 %). The diagnostic yield for EUS was higher than for MRCP (29 vs. 10.5 %). EUS more accurately detected biliary stones whereas MRCP identified pancreatic duct abnormalities, such as intraductal papillary mucinous neoplasm of the pancreas or chronic pancreatitis.

Conclusions: The combination of EUS and MRCP, when performed later after idiopathic acute pancreatitis, revealed 50 % of etiologies. The association of these two procedures and the subsequent follow-up reduced the rate of idiopathic pancreatitis by ~66 %.